Longer Marketing Time Increases the Risk of
Naturalization by Horticultural Plants
February 24, 2009
Plants that are mainstays of
horticulture also carry lots of risk, a new Agricultural Research Service (ARS) study
has found. Naturalization rates of non-native horticultural plants increase the
longer a plant is grown and sold.
Non-native horticultural plants, including most edible and landscape plants,
bring enormous benefit to the United States, but they are also a source of
invasive plants that harm our natural environments. Naturalized horticultural
plants are non-native plants that escape gardens and farms and are able to
survive independent of cultivation. Invasive plants are naturalized species
that invade natural areas, displace native plants and alter ecosystem
Pemberton, with the ARS
Plant Research Laboratory in Ft. Lauderdale, Fla., and his colleague Hong
Liu, formerly with the University of Florida,
analyzed a unique set of data from the detailed sales catalogs of an early
Florida plant nursery to detect naturalization patterns of horticultural plants
in the state. The data, which starts from the year 1887, accounts for more than
40 years of plant sales and examines more than 1,900 horticultural plants.
Unlike previous studies on the invasiveness of horticultural plants, the
research team found that the marketing period--the number of years a plant was
sold--has profound influence on naturalization and invasion. Seventy percent of
plants sold in Florida for 30 years or longer naturalized, according to
Pemberton, indicating that length of time sold is the most important factor
contributing to naturalization.
Non-native plants will continue to naturalize and invade as long as they are
sold. Therefore, according to Pemberton, risk assessments need to be developed
for screening non-native horticultural plants to identify non-invasive forms
and less-invasive alternatives.
Details of this study were recently published in the scientific journal
ARS is the principal intramural scientific research agency of the
U.S. Department of